Depending on the behavior, it may become automatic for you in about 66 days. Some habits may be more challenging than others, but persistence and consistency do help to develop new ones.

Whether you want to start a new habit or break an old one, it can be easier said than done. But how long does it actually take?

Some studies say under 20 days, while others say nearly 9 months. More on that below. With such a wide variation, it might be intimidating to approach starting a new habit, but there are things you can do to help reach your goals.

Read on to learn why it varies, what you can do to help maximize your efforts, and more.

According to an older 2009 study, it takes 18 to 254 days for a person to form a new habit. Other studies reported that, on average, it takes 66 days for a new behavior to become automatic.

The studies highlighted a range of variables in habit forming that make it impossible to establish a one-size-fits-all answer.

In a 2024 systematic review and analysis, emerging evidence on health-related habit formation shows that it can take about 2 months (about 60 days) to start forming a new habit. But it really varies among individuals and the complexity of the habit.

Some people are better suited to forming habits than others. A consistent routine of any kind isn’t for everyone, and that’s OK.

If asked how long it takes to form a habit, many people will respond “21 days.”

This idea can be traced back to Dr. Maxwell Maltz’s book “Psycho-Cybernetics,” published in 1960. Maltz didn’t make this claim but rather referenced this number as an observable metric in both himself and his patients at this time.

Maltz wrote: “These, and many other commonly observed phenomena, tend to show that it requires a minimum of about 21 days for an old mental image to dissolve and a new one to gel.”

As the book became more popular and millions of copies were sold, this situational observation became accepted as fact.

According to an older 2012 study, habits are actions triggered automatically in response to cues associated with their performance. For example, when you get into your car, you automatically put on your seat belt. Most people don’t think about doing it or why.

That might sound simple but habits are multifaceted, not simple stimulus-response behaviors, and involve multiple signaling mechanisms in the brain.

Your brain likes habits because they’re efficient. Automating common actions frees up mental resources for other tasks.

The brain likes efficiency and familiarity. Pleasure-based habits are particularly difficult to break because enjoyable behavior prompts your brain to release dopamine.

Dopamine is the reward that strengthens the habit and creates the craving to do it again.

As with many things in life, the first step is to become more aware of your habits so you can develop strategies to change them.

One strategy is to identify the places, people, or activities that are linked in your mind to certain habits, and then change your behavior toward those.

For example, if you have a substance use disorder, you can be deliberate about avoiding situations where you’d be more likely to be around the substance. This can help you achieve your goal of abstaining from using that substance.

Another strategy is to replace a bad habit with a good one. For example, instead of snacking on potato chips, consider swapping for unsalted, unbuttered popcorn. Instead of reaching for a cigarette, consider trying a new flavor of chewing gum or a flavored hard candy.

Getting specific and making SMART goals, often used in fitness, is also helpful.

It can take anywhere from 18 to 254 days for a person to form a new habit, and an average of 66 days for a new behavior to become automatic.

There’s no one-size-fits-all figure, which is why this time frame is so broad. Some habits are easier to form than others and some people may find it easier to develop new behaviors.

There’s no right or wrong timeline. The only timeline that matters is the one that works best for you.